The present invention relates to a process for extracting cobalt, copper or nickel values from ammoniacal process solutions, and more particularly, to a process for extracting cobalt, copper or nickel values from ammoniacal solutions with a chelate exchange resin.
Processes for extracting metal values, including nickel and cobalt, from aqueous solutions with organic extractants are well known in the art. For example, there is disclosed in U.S. Pat. No. 2,993,782 to Hampton et al. a process for extracting cobalt, copper or nickel values from ammoniacal solutions with chelate exchange resins. The chelate exchange resin comprises a water-insoluble, water-swollen, solid polymeric resin containing recurring units of at least 80 percent by weight which correspond to an ar-vinylbenzylamino dicarboxylic acid. Metal values loaded on the chelate exchange resin are stripped therefrom by contact with an aqueous solution of a mineral acid. The stripped chelate exchange resin is treated with an aqueous solution of ammonium sulfate or ammonium chloride before being recycled to recover further quantities of the metal values.
Experience has shown that the class of organic extractants taught by Hampton et al. are gradually degraded. Actual use of iminodiacetate chelate exchange resins for periods over a year have shown that such resins can lose 30% or more of their loading capacities. Hampton et al. did not recognize this problem nor did they offer any solution.